Dyeing with quinones or hydroquinones and borohydrides and compositions therefor



United States DYEING WITH QUINONES R HYDROQUINONES AND BOROHYDRIDES AND CONIPOSITIONS THEREFOR Raymond Stanley Max Frohnsdorlf, Twickenham, and John Upton Lewin, Isleworth, England, assignors to The Gillette Company, Boston, Mass., a corporation of Delaware No Drawing. Application October 6, 1954, Serial No. 460,776

Claims priority, application Great Britain April 30, 1954 8 Claims. (Cl. 167-88) This invention is for improvements in or relating to the production and/ or stabilization of hydroquinones and has for an object to provide stabilized solutions of hydro quinones which, inter alia, may be useful for the preparation of solutions for the dyeing and tinting of hair.

Many substances useful in the dyeing and tinting of hair are quinone compounds of the benzene and naphthalene series, but many of these quinones are either themselves unstable or are insufiiciently soluble in water to allow the preparation of solutions of a high enough concentration to provide an elfective dyeing solution.

For example, the natural dyes contained in henna have to be applied to the hair by padding, which involves preparing a moistened mass of the natural henna-containing vegetable material and applying it directly to the hair.

The present invention makes it possible readily to reduce such difiiculty soluble quinones to the more soluble hydroquinones, thus making it possible to prepare dyeing and tinting solutions of much higher concentration than is possible with the natural product.

According to the present invention, therefore, there is provided a process for the reduction of quinones and/or the stabilization of hydroquinones which comprises treating the quinones or hydroquinones with an aqueous alkaline solution of an alkali metal borohydride such as sodium or potassium borohydride. The borohydrides may generally be employed for reducing and solubilizing the oxidized form of oxidative dyestuffs such as vat dyes which form leuco-compounds, as well as for stabilizing aqueous solutions of the reduced or leuco-form of the dye. The invention also includes stabilized solutions of hydroquinone comprising and aqueous alkaline solution containing the hydroquinone and an alkali metal borohydride. In its adaptation to the dyeing or tinting of hair, the hydroquinones in aqueous solutions may be considered to be leuco-dye compositions. They are applied to the hair and are then, in situ, or immediately previously, converted by oxidation to their quinone form, in which form they effectively dye or tint the hair.

Accordingly, the invention also provides a process for the preparation of solutions for the dyeing and tinting of hair which comprises producing and/or stabilizing a hydroquinone by adding to the hydroquinone or to the quinone corresponding thereto in an aqueous medium an amount of alkali metal borohydride such as to maintain the hydroquinone substantially stable and maintaining the pH of the solution above 7. The amount ofthe alkali metal borohydride, preferably potassium borohydride, is such as to prevent the development of color in the hydroquinone solution, or at least to minimize the development of color in the solution.

To render the solution ready for application as a hair dyeing or tinting preparation, the alkali metal borohydride present in the stabilized hydroquinone solution is preferably destroyed by a reduction of its pH value below pH 7,

2,745,?88 Patented May 15, 1956 and this may be done either in situ or before application to the hair.

While the solutions are particularly suitable for the 401,057 filed January 1, 1953, we have described the use of trihydroxy toluene and trihydroxy benzene, respectively, as agents for the dyeing of keratinous material, the inventions residing in the application of these two trihydroxy aromatic substances to the hair in association with one or more primary aliphatic or aryl aliphatic amines or salts thereof at pH values ranging between 5 and 12.

The present invention may be combined with the inventions of our prior applications, and according to a feature of the present invention, the stabilized hydroquinone solution is admixed with a primary aliphatic or aryl aliphatic amine or salt and is then applied to the keratinous material, e. g., hair, the alkali metal borohydride being destroyed in situ or prior to application by adjustment of the pH value of the solution.

The reduction of the quinone compound by the action of the alkali metal borohydride in most instances proceeds readily by the addition of the alkali metal borohydride to an aqueous solution or suspension of the quinone, but with some compounds it has been found an advantage to add alcohol or a small quantity of an alkaline material in order to speed up the rate of reduction. Thus, benzoquinone is readily reduced if first dissolved in alcohol, but reduces only slowly if suspended in Water at room temperature. Quinones containing solubilizing substituents, however, will rapidly reduce when the reaction is carried out in water alone; for example, hydroxybenzoquinone is immediately reduced by the action of the potassium borohydride.

Among the various quinones to which the present invention has been applied, there may be mentioned the following: hydroxybenzoquinone, methoxybenzoquinone, 2: aminobenzoquinone, 2 5-bis-diethylaminobenzoquinone,

anilinoquinone, 2:S-dihydroxybenzoquinone, 2:5-dimeth-- oxybenzoquinone, chloroquinone, 1:4-naphthoquinone, lawsone, juglone, menaphthone, 2-amino-1z4-naphthoquinone, 1:4-naphthoquinone-4-sulfonate sodium salt, 2:3- dichloro-l:4-naphthoquinone, naphthazarin, indigo, and alizarin.

The invention has been applied with success to hydroxynaphthoquinones; namely, lawsone, juglone, and naphthazarin. The lawsone and juglone are preferably ground to a fine powder before treatment with the aqueous borohydride solution and then, on mixing with the alkali metal borohydride solution, a rapid reduction occurred. There is a tendency for foaming to occur, and this foaming maybe particularly severe when the pH of the solution is re-- duced in order to destroy any excess of the alkali metal borohydride. The diiiiculty with foaming is minimized or avoided by carrying out reduction in an aqueous alcoholic medium or by adding an antifoaming agent; for example,

the silicone anti-foaming agent sold as Silicone D. C. Anti-foam A.

Although it is preferable, as pointed out above, to destroy the borohydride by reducing the pH of the composition below pH 7 before application to the hair in order to avoid possible irritation to the skin by the borohydride,

dyeing may be successfully carried out even with borohydride present in the composition, in which case, of course, the pH must be at least 7. The color imparted to the hair or other keratinous material may readily be controlled by adjusting the pH of the composition (either before or after destruction of the borohydride) before the composition is applied to the hair. The compositions may:- 5

Example 1 1.14 g. of lawsone and 0.70 g. of potassium borohydride were ground together in a mortar and then six portions of this mixture, each of 0.25 g., were weighed into dry test tubes; ml. of water were added and after a few minutes colorless solutions were obtained. Although an appreciable evolution of gas took place, no foam was produced. Subsequently the solutions were treated as follows:

(i) 3. ml. of 0.5 N hydrochloric acid added and when evolution. of gas ceased 5 ml. of water added.

(ii) 3 ml. of 0.5 N hydrochloric acid added and when evolution of gas ceased 5 ml. of 0.2 M sodium succinate added.

(iii) 3. ml. of 0.5 N hydrochloric acid added and when evolution of gas ceased 0.75 ml. 0.2 M sodium carbonate and 5 ml. 0.5 M phosphate buffer which had previously been adjusted to pH 8 added.

(iv) 1.5 ml. 0.5 N hydrochloric acid added and when evolution of gas ceased 5 ml. 0.5 M phosphate bufferat pH 8 added.

(v) 5 ml. of 0.5 M phosphate buffer at pH 8 added.

(vi) 3 ml. 0.5 N hydrochloric acid added and when evolution of gas ceased 5 ml. of 0.2 M sodium carbonate added.

A small tress of grey hairand a small square of wool cloth were soaked in each solution for 5 minutes before exposure to the atmosphere for 30 minutes followed by a water rinse and a scour with a detergent.

The dyeing results were similar to those obtained from 1:2:4-trihydroxynaphthalene at the same pH values with the usual intense orange colors from acid solutions. The pH' values of the solutions were: (i): 1.8, (ii) 5.7, (iii) 7.4, (iv) 85, (v) 9.9, and (vi) 8.9. The presence of the reductant during dyeing (v) didnot influence the result. It will be appreciated that the hydroquinone is a dye-precursor which is converted to the dye (hydroxynaphthoquinone) by oxidation in the air.

Example 2 acted acid, it was found that cloth, and also a tress of grey hair, could satisfactorily be dyed yielding an intense orange coloration.

Example 3 1.14 g. of juglone and 0.70 g. of potassium borohydride were ground together and 0.28 g. samples of the mixturewere used for each experiment in the same way as that described in Example 1.

The tendency to foaming waseffectively controlled by the addition of a drop of the anti-foaming agent, Silicone D. C. Anti-foam A, referredv to above and the pl-l values of the several solutions. were adjusted as in Example 1 and gave valuesasfollows: (i) 2.2, (ii) 6.6, (iii) 8.2, (iv) 9.2 (v) 10.2 and (vi) 9.2.

Example 4' The procedure described in. Example: 1 was repeated using 1.24 g. of naphthazarinin placeof the lawsone and utilizingsamples each of 0.30i g. in the same way as in 4. Example 1 in 50% aqueous alcohol solution instead of aqueous solution.

A dull yellow to green solution was obtained after a short time and the six samples were then adjusted as to their pH as described in Example 1, the six samples having the following pH values: (i) 3.3, (ii) 6.0, (iii) 7.8, (iv) 8.0, (v) 9.8, and (vi) 8.2. On applying the'solution to the cloth and hair as previously described, it was found that the shade of dyeing was dependent on the pH of the dye solution, varying from a light red-brown from acid solution to a strong purple, to grey on alkaline solution.

Example 5 In this example, 1:2:4-trihydroxybenzene (THB) and mixtures thereof with lawsone were examined; these experiments were carried out by adding powder mixtures of the following composition to 50 ml. of water:

(a) 0.63 g. THB and 6.75 g. sodium succinate.

(b) 0.47 g. THB, 0.22 g. lawsone, 0.078 g. potassium borohydride, and 6.75 g. sodium succinate.

(c) 0.32 g; THB, 0.44 g. lawsone, 0.14 g. potassium borohydride, and 6.75 g. sodium succinate.

(d) 0.16 g. T'HB, 0.65 g. lawsone, 0.21 g. potassium borohydride, and 6.75 g. sodium succinate.

Rapid solution and reduction occurred to give colorless solutions. and the initial evolution of gas soon subsided due to the rapid destruction of the reducing agent in the presence of the neutral buffer.

Grey hair and cloth were dyed with the solutions togive colors varying from a medium-strong brown to strong orange.

Similarexperiments relating to mixtures Were carried. out with mixtures of lawsone and juglone, juglone and naphthazarin, and with lawsone, juglone, and naphthaza rin; in each case the dyes appeared to act additively atpH values ranging from 1.6. to 9.8.

It will be appreciated that the present invention provides. an important advance in the dyeing and tinting of hair... in particular rendering it possible to prepare concentrated stable. dyeing preparations from the relatively insoluble quinon-e compounds by converting these quinones to the corresponding hydroquinone and thereafter reoxidizing them, preferably in situ, and preferably with the addition of the primary amines above referred to. Moreover, the. use of the'borohydride avoids the. disadvantages associated with the usev of the more usual reducing agents, such as sodium dithionate andstannous chloride, in the treatment of hair.

Variations in. the; actual dyeing technique may be adopted; for example, instead of or in addition to the use of the above-mentioned amines, oxygen carrier substances may be used; for example, intense dyeing tints may be obtainedif a ferrous compoundis used as an oxygen carrier.

The solutions for use as dyeing preparations may bemade in. varying concentrations, thereby renderi'ngpossible a close control ofthe shade towhich the keratinous material is. dyed;

Although specific embodiments of the inventionhave been. herein described, it is not intended to limit the invention solely thereto, but to include all of the obvious variations and modifications within the spirit and scope 4. A stable leuco-dye composition comprising in aqueous solution a hydroquinone and a member of the class consisting of sodium and potassium borohydride at a pH of at least 7.

5. The method of preparing a stable reduced solubilized aqueous solution of a quinone dye which comprises reacting the oxidized form of the dye with a member of the class consisting of sodium and potassium borohydride in an aqueous medium at a pH of at least 7.

6. The method of preparing a stable aqueous solution of a hydroquinone which comprises reacting a quinone with a member of the class consisting of sodium and potassium borohydride in an aqueous medium at a pH of at least 7.

7. The method of dyeing a keratinous material which comprises reducing the oxidized form of a quinone dye with a member of the class consisting of sodium and potassium borohydride in an aqueous medium at a pH of at least 7, and applying said reduced dye to the keratinous material.

8. The method of dyeing hair which comprises reducing a quinone to a hydroquinone by reaction with a member of the class consisting of sodium and potassium borohydride in an aqueous medium at a pH of at least 7, and applying said aqueous medium containing said hydroquinone to the hair.

References Cited in the file of this patent UNITED STATES PATENTS 2,461,661 Schlesinger Feb. 15, 1949 2,534,533 Schlesinger Dec. 19, 1950 2,576,311 Schlesinger Nov. 27, 1951 OTHER REFERENCES Krajkeman: Reduction of Org. Compds. with Lithium Al Hydride, Mfg. Chemist, Apr. 1951, pp. 147-153.

Hochstein: Quant. Studies on Lithium Al Hydride Reactions, J. A. C. 8., vol. 71, 1949, pp. 305-307.

Bulletin 502A, Sodium Borohydride, Metal Hydrides, Inc., Beverly, Mass., 2 pages., received Feb. 15, 1950.

Finholt: Lithium A1 Hydride I. A. C. S., May 1947,.pp. 1199-1203, esp, at page 1200, comparing properties of lithium aluminum hydride with those of lithium borohydride.

Redgrove: Hair-Dyes and Hair-Dyeing, Chem. Publ. Co., N. Y., 1939, pp. 69-75, esp, at page 72. 

1. A REDUCED SOLUBILIZED AQUEOUS QUINONE DYE COMPOSITION STABILIZED WITH A MEMBER OF THE CLASS CONSISTING OF SODIUM AND POTASSIUM BOROHYDRIDE. 